A technique for the estimation of the turnover rate of GABA (TRGABA) using gas chromatography and mass fragmentography has been applied to the study of the interrelationship between dopamine and GABA in the striatum and N. Accumbens. The effect of electroconvulsive shock (ECS) on TRGABA in various regions of the brain has also been studied. Our results show that electrical stimulation of the head of N. caudatus produces a significant increase in the TRGABA in the substantia nigra. However, stimulation of the substantia nigra does not have a clear effect on the TRGABA of homolateral N. caudatus suggesting an indirect relationship between dopaminergic input to these nuclei and local GABA neuronal regulation. Contralateral caudate is however affected during an indirect connection probably via cortex. In rats, repeated ECS0 increases GABA concentrations in the N. caudatus and N. accumbens and decrease the TRGABA by 40% and 50%, respectively, in these regions. Subconvulsive shocks have no effect. No consistent changes have been seen in substantia nigra.